Horologium is a tall brown grandfather clock with long, black arms, a glass case, a Roman-numerical clock at the center and a small face at the top with slit eyes and a thin, twirly, mustache-like mouth. The glass case serves as protection for the one who is inside and Lucy usually uses this to protect herself from the cold. This case prevents anyone outside from hearing what the person inside is saying, so Horologium repeats everything the person inside says and then follows with a "...he/she/they say/s." In the case of multiple people inside he will make specific details on whoever is currently talking.

Little is known about his individual personality, as he almost only repeats what his owners say. It is clear though, that he deeply cares for his owner and even his owner's friends, as he has a habit of forcefully summoning himself to protect them.

Defense Magic: Horologium wields Defense Magic that allows him to keep people safe within his clock body and narrate for those inside him. He can be used in both non-combative and combative situations. Lucy uses him as shelter and transport when traveling in snowy and muddy areas. In combat, he can protect the person inside him even a dangerous environment such as lava with his hard, wooden body. However, Horologium does not seem to have combative moves. He is also mostly on a time limit: he will transport back to the Celestial Spirit World once the time is up, leaving his occupant behind, regardless of any danger he or she may be in.

Automatic Danger Response Mode: Horologium forcefully summons himself when he detects a severe danger about to occur, and shields the person's body in himself. This was used to save Wendy Marvell from Hades' Katsu spell. It is also possible Horologium did this when he saved Lucy from being sucked up by the Anima. It will however, take him some time to reuse it.

Self Summoning: In correlation to his Defense Magic, he is also able to force-open his gate, usually to aid Lucy and/or her friends.

Immense Durability: Horologium is shown to have immense durability; he is able to completely submerge himself in lava and only sustain minor burns. In the Fairy Tail anime this is further enhanced with Horologium sustaining no visible damage at all whilst submerged.

Healing Abilities: As stated by Horologium, he can cure the following: lack of oxygen, bug bites, chapping skin, itchiness and skin spots.

Immortality: As a Celestial Spirit, Horologium cannot die unless he is somehow forced to stay in the Human World.